In the 1970 Owens-Corning Fiberglas introduced a door which was made with fiberglass skins composed of polyesters and glass fibers thin sheets. These sheet were then mounted on a rectangular frame composed of rails and stiles with adhesives and the resulting hollow core filed with a plastic foam, such as polyurethane foam. The product was a very viable door but its advantages, such as higher insulating values, were not enough to off set the high prices, even though the doors did not chip, crack or warp, according to a brochure published by the Owens-Corning Fiberglas at that time. In 1976 a patent issued to DiMaio, U.S. Pat. No. 3,950,894 which describes a synthetic door product, as a polyester door composed of two glass fiber reinforced polyester skins supported on a frame with the hollow core filled with a plastic foam.
Since the mid-1970's the costs of making fiberglass skins by sheet compression molding techniques have dropped appreciably even though such techniques have been known for some time, e.g. see U.S. Pat. No. 3,772,241 issued to Kroexel defining one type of molding composition for such processes, and doors made with such skins have become more competitive with natural wood products, which have actually increased in prices since the mid-1970s As a result there now is considerable interest in marketing synthetic door products produced by employing compression molded thin skins mounted on a frame with the hollow core between skins filled with a plastic foam.
Due to the potential of the market a number of patents have issued in this area, such as U.S. Pat. Nos. 4,550,540; 4,901,493; 4,965,030; 4,860,512 and 4,864,789 issued to Thorn, along with U.S. Pat. No. 5,074,087 issued to Green. Of course such structures are not limited to entry and exit doors in buildings but can also be used on cabinet doors and drawers, such as shown in U.S. Pat. No. 3,498,001 issued to McDonald and U.S. Pat. No. 3,402,520 issued to Lee.
U.S. Pat. Nos. 4,901,493 and 4,720,951 issued to Thorn teach insert of panels door casement made with compression molded skins, such as panes, which is the area to which this invention relates.
More particularly this invention involves the construction of door casements of synthetic materials using compression molded skins which have a large aperture for receiving a heavy pane of glass, such as double glazed glass panes, that are mounted on an outer frame and an inner frame to construct patio doors and the like, in which the resulting casements will have sufficient mechanical strength to support such heavy panes; the hollow rectangular core is filled with a plastic foam to increase the insulating qualities of the door casement and increase its overall integrity since the foam adheres to the inside surfaces of the skins.
An advantage besides the strength of the door casements, is the economics of constructing multiple sizes of such casements from the same small mold or molds.
Other advantages will be apparent from this specification when read in conjunction with the attached drawings illustrating the invention.